The technologically useful properties of a solid often depend upon the defects it contains. Despite the harmful sound of "defects," their types and concentrations can be precisely tuned to enhance device performance. For example, silicon-based integrated circuits rely upon defects such as vacancies and interstitials to mediate the diffusion of dopant atoms that are critical to device performance. Defects in TiO2 and ZnO affect the performance of photoactive devices, effectiveness of catalysts and photocatalysts, sensitivity of solid-state electrolyte sensors, and efficiency of devices for converting sunlight to electrical power.
Since defects affect many aspects of semiconductor behavior, the ability to control the type, concentration, spatial distribution, and mobility of such defects is important for practical applications. The practice of such control is termed "defect engineering." Considerable progress has been made in developing this ability for silicon, but the methods still need considerable development for other semiconductors such as metal oxides.
Research in this group focuses on developing new methods for defect engineering in semiconductors to make nanoscale devices of interest for energy, environmental, and microelectronics applications. We have discovered several new physical mechanisms to accomplish this control that work well at small length scales below about one micrometer. The mechanisms include photostimulation and reactions of defects at surfaces. Our work employs both experiments and computations to develop a fundamental science base while simultaneously applying the findings to practical applications.
A text in engineering ethics: Fundamentals of Ethics for Scientists and Engineers
A text in charged defects: Charged Semiconductor Defects: Structure, Thermodynamics and Diffusion
A unique instructional program in semiconductor processing